OEM 13c EMGC_ADMINSERVER & EMGC_OMS1 target status show DOWN when emctl secure wls with cut certificate

 When custom certificate is configured for OEM 13c, WebLogic Servers installed as part of Enterprise Manager Cloud control (Administration Server and Managed Servers) can be secured with custom certificate using following command,

   $OMS_HOME/bin/emclt secure wls

However, the WebLogic Servers and their deployments could show down in OEM console after secured with custom certificate, though they are still running well.

The reason is that the CA involved in issuing the custom certificate for OMS is not "well known", at least it is not accepted by Oracle as default trusted CA. When agent running on OMS server communicates with WebLogic Servers (WLS), WLS is using the custom certificate as his own identification, but agent cannot find trusted certificates of CA involved in issuing the custom certificate from agent's local keystore. Therefore, agent cannot verify the validation of WLS's certificate, and stops the communication with WLS.

The quick fix is to import the certificate of each CA involved in issuing the ticket into agent local keystore with following command,

    $AGENT_HOME/bin/emctl secure add_trust_cert_to_jks -trust_certs_loc <ca_certificate_file> -alias <certificate_alias> [-password <keystore_pwd>]

Here, <certificate_alias> is used to identify the certificates saved in the keystore, they must be unique for each certificate, <keystore_pwd> is the password of the keystore, the default value is welcome.

For example, I have installed a CA in my lab network, and the CA issued certificate to my OMS server. The two of my CA server certificates (root certificate & intermediate certificate) has to be imported into agent keystore as following,

 $AGENT_HOME/bin/emctl stop agent

 $AGENT_HOME/bin/emctl secure add_trust_cert_to_jks -password welcome -alias dbaplus-root -trust_certs_loc /home/oracle/Root_CA_Certificate.txt

 $AGENT_HOME/bin/emctl secure add_trust_cert_to_jks -password welcome -alias dbaplus-intermediate -trust_certs_loc /home/oracle/Intermediate_CA_Certificate.txt

 $AGENT_HOME/bin/emctl start agent

List the certificates imported into agent monitor keystore,

 $AGENT_HOME/jdk/bin/keytool -list -alias <certificate_alias> -keystore   $AGENT_INSTANCE_HOME/sysman/config/montrust/AgentTrust.jks -storepass welcome -v

If needed, the certificates can be removed from keystore as following

 $AGENT_HOME/jdk/bin/keytool -delete -alias <certificate_alias> -keystore   $AGENT_INSTANCE_HOME/sysman/config/montrust/AgentTrust.jks -storepass welcome -v